Avian Pox in Birds: Signs, Transmission and Supportive Care

Avian pox is a viral disease found in birds around the world. It can affect poultry, pigeons, parrots, canaries and many wild bird species, including native New Zealand birds.

One of the interesting things about avian poxviruses is that they tend to show a degree of host specificity. Different strains are adapted to particular groups of birds, although transmission between species can occur in some circumstances.

How Does Avian Pox Spread?

Avian pox is particularly likely to become a problem where birds congregate, including backyard flocks, aviaries, pigeon lofts, rehabilitation facilities and nesting colonies.

The virus usually needs an entry point through the skin. Small scratches, wounds and insect bites can provide this opportunity.

Transmission can occur through:

• Mosquitoes and other biting insects
• Mites and other arthropods
• Direct contact with infected lesions
• Contaminated surfaces and equipment
• Virus-containing scabs and environmental material

Scabs shed from affected birds can contain large amounts of virus and contaminate the environment, making hygiene and isolation particularly important.

Clinical disease usually develops after an incubation period of several days, and lesions may persist for several weeks.

What Does Avian Pox Look Like?

Avian pox generally occurs in two main forms, although both can occur in the same bird.

Dry or Cutaneous Pox

This is the form most bird owners recognise.

Raised nodules and crusting lesions develop on areas of exposed skin, particularly around the:

• Eyes
• Eyelids
• Beak
• Comb and wattles
• Feet and legs
• Other unfeathered areas

Lesions often enlarge before drying and forming characteristic scabs.

Depending on their location and severity, they can interfere with vision, feeding, movement or normal tissue function. Severe lesions can also become damaged or secondarily infected.

Wet or Diphtheritic Pox

Wet pox affects the tissues of the mouth, throat and upper respiratory tract.

Yellowish or white plaques and membranes can develop within the oral cavity. These lesions may interfere with eating, drinking or breathing.

They can also be firmly attached to the underlying tissue, so attempting to pull them off can cause significant bleeding and tissue damage.

Wet pox can be considerably more serious than uncomplicated cutaneous disease, particularly if lesions begin obstructing the airway.

How Serious Is Avian Pox?

Severity varies enormously.

Some birds develop only a handful of small skin lesions and recover with minimal intervention. Others can develop extensive lesions that compromise the eyes, beak, feet, mouth or respiratory tract.

The outcome can be influenced by:

• The strain of virus
• The bird's immune status
• Age and general condition
• Location and extent of the lesions
• Secondary bacterial or fungal infections
• Ability to continue eating and drinking

Young, debilitated and immunocompromised birds can be particularly vulnerable.

Is There a Treatment for Avian Pox?

There is no specific antiviral treatment that eliminates avian pox, so management largely revolves around supportive care while the bird's immune system controls the infection.

Depending on the individual bird, supportive care may include:

• Providing warmth and a quiet hospital environment
• Monitoring body weight
• Ensuring adequate food and fluid intake
• Providing nutritional support when required
• Appropriate pain relief
• Keeping lesions clean and protected
• Managing secondary infections when present

Antibiotics do not treat the poxvirus itself. They may occasionally be prescribed by a veterinarian when a secondary bacterial infection is present.

Lesions around the eyes, beak or mouth require particularly careful monitoring.

When Does a Bird With Pox Need Veterinary Help?

Veterinary assessment becomes particularly important when:

• The bird stops eating or drinking
• Body weight begins falling
• Lesions involve the mouth or throat
• Breathing becomes difficult
• An eye is affected
• Lesions interfere with the beak or feet
• There is evidence of secondary infection
• The bird becomes weak or systemically unwell

Severe respiratory obstruction or extensive disease can become life-threatening.

Preventing Avian Pox

Prevention focuses heavily on reducing opportunities for transmission.

Control Biting Insects

Mosquitoes and other biting insects can mechanically transmit avian pox between birds.

Reduce standing water, maintain good environmental hygiene and manage insect populations where practical.

Maintain Good Biosecurity

Avoid sharing contaminated equipment between groups of birds and clean housing, feeders, waterers and handling equipment appropriately.

New or affected birds should be isolated from the rest of the flock.

Be Particularly Careful With Scabs

Pox scabs contain infectious viral material and can contaminate the environment.

Avoid unnecessarily disturbing lesions, and use good hygiene when handling affected birds or cleaning their housing.

Avian Pox in Bird Rehabilitation

Pox is particularly important in rehabilitation facilities because susceptible birds from multiple species may be housed within the same facility.

Affected birds should be appropriately quarantined, with dedicated equipment and careful attention to cleaning, handling order and insect control.

Even relatively mild cases can become a significant biosecurity problem when multiple vulnerable patients are being cared for in the same space.

What About Vaccination?

Vaccines are available for some avian poxviruses, particularly those affecting commercial poultry.

Whether vaccination is appropriate or practical depends on the species, flock and circumstances. For most backyard bird owners and wildlife rehabilitation situations, prevention instead centres around biosecurity, insect control and rapid isolation of affected birds.

The Takeaway

Avian pox can look alarming, particularly when large lesions develop around the face, but many birds can recover successfully with appropriate supportive care.

The location of the lesions matters just as much as their size. A relatively small lesion affecting the eye, mouth or airway may be much more significant than several larger lesions elsewhere on the body.

Good supportive care, insect control and strict biosecurity are the foundations of managing avian pox.

Written by Dr Sam Hurley, BSc, BVSc, MAHM